1. Field of the Invention
The present invention relates to a system for stock rotation of liquids, such as soft drink syrups, contained in collapsible bag-type reservoirs or replaceable packages. More specifically, the present invention relates to an improved automatic change-over valve for automatically switching between a primary supply reservoir and a secondary supply reservoir in response to an empty condition of the primary reservoir.
2. Description of the Prior Art
Heretofore the stock rotation or changing of liquid bag packages such as milk, soft drink syrups or chemicals, has been accomplished by manual methods. When the contents of a package are exhausted, the pump system was not supplied with liquid until the packages could be manually changed. This caused unavoidable, unexpected and inconvenient delays in the dispensing operation. To provide for larger reserves many prior art systems connected packages in a parallel arrangement. However, this parallel arrangement does not provide for the necessary stock rotation required by many perishable food items such as milk and soft drink syrups. By contrast, conventional rigid type sealed packages have inlet and outlet openings and are often connected in series. However, this system also does not provide for a complete rotation of the liquid products since mixing occurs. Furthermore, if bag packages according to the present invention were connected in series, they would not provide for reserve capacity but only a large initial capacity, since the bag packages would collapse equally unless assisted by gravity or other external means.
Automatic change-over devices for non-viscous liquids disposed in open or vented rigid containers are known in the prior art. However, these devices are not satisfactory for automatic stock rotation of viscous liquids contained in flexible bag packages. Furthermore, many liquids tend to crystalize when exposed to air in open systems, this further complicates container rotation. Bag packages, according to the present invention, overcome the deficiencies of the prior art containers by providing a sealed and closed system to air and other outside contaminates.
For example, an automatic change-over system for gas contained in a primary and secondary bank of storage tanks is disclosed in U.S. Pat. No. 2,968,162 to Acomb issued Jan. 17, 1961. The Acomb system effects a change-over from one group of supply tanks to another in response to pressure changes caused by an empty condition of the tanks being dispensed. However, the Acomb system does not possess the necessary sensitivity to automatically dispense more viscous liquids, such as syrups, in a fast and reliable manner.
Another similar type of automatic change-over system is disclosed in U.S. Pat. No. 3,825,027 to Henderson. In the Henderson system, the change-over sensitivity is enhanced by the provision of ball float valves 34, 36 in the respective primary and secondary supply circuits. The Henderson system works very well for dispensing liquid fuels of low viscosity, this being the purpose for which it was designed. However, the float valves tend to stick due to sugar build-up when the liquid being dispensed is a viscous liquid such as soft drink syrups.
Another automatic change-over device for a liquid dispensing system is disclosed by Harvill, U.S. Pat. No. 4,014,461 and assigned to the same assignee as the present invention. Harvill discloses an automatic change-over system for stock rotation of a liquid product packaged in collapsible bag-type reservoirs. However, the automatic change-over valve employed in the system disclosed by Harvill is rather complicated and extremely bulky.